1. Field of the Invention
The present invention relates to an improved camera system including a camera main body and an accessory mountable on the camera main body, wherein the camera main body can perform communication between the camera main body and the accessory and can supply power to the accessory.
2. Description of the Related Art
In a camera system composed of a camera main body and an accessory mountable on the camera main body, the accessory has been arranged heretofore such that it is operated by power supplied from the camera main body. Japanese Patent Publication No. 2546220, for example, discloses a camera system in which camera size is reduced, the number of parts is decreased, and cost is lowered by using a common power supply terminal, and by making it unnecessary to increase the number of terminals even if different types of AF lenses are mounted thereon.
In this type of camera system, the power supply voltage which can be used by the accessory is determined from the state of a contact between a camera main body and the accessory. The voltage is determined based on whether or not a response is returned from the accessory to the camera main body when a signal is supplied to the accessory from the camera main body. Therefore, only two types of voltages can be determined, which is not suitable for determining a voltage which can be used by an interchangeable lens mounted on the camera main body accurately and promptly, when there are many interchangeable lenses which are operated at different voltages.
One aspect of this invention relates to a camera system composed of an accessory and a camera main body. The accessory can be mounted on the camera main body and includes a communication unit for performing communication between the accessory and the camera main body. The camera main body includes a power supply unit capable of supplying power having a plurality of different voltages (e.g., voltage levels) to the accessory and a communication unit for performing communication between the camera main body and the accessory; the camera main body determines the voltage of the power to be supplied to the accessory based on a result of communication with the accessory. This invention thus relates to a camera system capable of correctly and promptly supplying power from the camera main body to the accessory even if the system uses a plurality of accessories which require either two types of power supply voltages or three or more types of power supply voltages.
One aspect of this invention relates to a camera system composed of a camera main body and an accessory, where the accessory is mountable on the camera main body and has a communication unit through which communication is performed between the accessory and the camera main body and a CPU, the power consumption of which is reduced when a voltage higher than a voltage necessary for normal operation thereof is supplied thereto, and where the camera main body includes a communication unit for performing communication between the camera main body and the accessory. When the accessory is in a waiting state, the camera main body supplies power, a voltage of which is higher than a voltage with which the CPU of the accessory performs normal operation, to the accessory so that the power consumption of the CPU of the accessory is reduced. This invention thus provides a camera system in which power consumption of the accessory is reduced when the accessory is in the waiting state.
One aspect of this invention relates to a camera which includes a communication unit for performing communication with an accessory mounted on the camera and a power supply unit for supplying power having a plurality of different voltages (e.g., voltage levels) to the accessory and determines the voltage of the power to be supplied to the accessory based on a result of communication with the accessory. This invention relates to a camera capable of correctly and promptly supplying power to an accessory even where the camera is usable with a plurality of accessories which require either two types of power supply voltages or three or more types of power supply voltages.
One aspect of this invention relates to a camera composed of a communication unit through which communication is performed with an accessory mounted on the camera and a power supply unit for supplying power to the accessory. When the accessory is in a waiting state, the power supply unit supplies power, a voltage of which is higher than a voltage with which the accessory performs normal operation, to the accessory so that the power consumption of the accessory is reduced. This invention thus relates to a camera in which power consumption of the accessory is reduced when it is in the waiting state.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.